Ancient Europeans were lactose intolerant for 5,000 years after switching over to agriculture. DNA extracted from skulls dating from 5,700 BC to 800 BC shows that Europeans carried the genes for lactose intolerance. But that didn't stop them from eating dairy products like milk and cheese for 4,000 years. The study shows that genomes can shift as new technologies emerge.
(image: Africa Studio/Shutterstock)